The present invention relates to an endoscopic diagnosis system for simultaneously acquiring and displaying a narrowband light image for blood vessel observation and a narrowband light image for oxygen saturation level observation as special light observation.
There is conventionally used an endoscope device wherein white light (normal light) emitted from a light source device is guided to the tip of an endoscope to illuminate a region under observation of a subject, and the reflected light is imaged to acquire a normal light image (white light image) in order to perform normal light observation (white light observation). In recent years, however, there is used an endoscope device wherein a region under observation of a subject is illuminated with narrowband light (special light) having a given wavelength range, and the reflected light or the like is imaged to acquire a special light image in order to perform special light observation in addition to normal light observation.
An endoscope device capable of special light observation can readily visualize biological information which is unobtainable from a normal observation image, for example, the fine structure of a new blood vessel formed in a mucosa layer or a submucosal layer in a subject's lumen and an enhanced site of lesion. When, for example, the site to be observed is a cancer-affected region, illuminating a mucosa tissue with blue narrowband light enables observation of the states of fine blood vessels and the fine structure in the superficial layer of a tissue in greater detail and thus permits diagnosis of a site of lesion with an increased accuracy.
In endoscopic observation, by switching among, for example, a normal light image, an image of blood vessel arrangement (narrowband light image for blood vessel observation) and an oxygen saturation level image of an affected region/blood vessel on a display to compare, diagnostic performance on the affected region can be effectively improved. JP 1-43228 A discloses an electronic endoscope device which switches between, for example, a normal light image and an image of blood vessel arrangement or between a normal light image and an oxygen saturation level image on a display, using an image sensor such as a CCD (Charge Coupled Device) having a color separation filter in combination with a rotary filter having different separation/transmission characteristics from the color separation filter.
First, the electronic endoscope device disclosed in JP 1-43228 A which switches between a normal light image and an image of blood vessel arrangement on a display is described below with reference to a conceptual view illustrated in FIG. 13.
When observing a normal light image, in light having wavelength range of visible light range to infrared light range emitted from a lamp, light having wavelength range of the infrared light range is cut off by an infrared cut filter, and light in the visible light range only illuminates a subject. The light reflected on the subject is then separated into colors of cyan, green and yellow at a time by an image sensor having a color filter with spectral transmission characteristics that transmits cyan (Cy) light, green (G) light, yellow (Ye) light and infrared (IR) light, respectively, and is imaged. The process generates a video signal of a normal light image (color display).
When observing an image of blood vessel arrangement, light having wavelength range from visible light range to infrared light range emitted from a lamp is sequentially turned, by a rotary filter, into light in three wavelength ranges IR1, IR2 and IR3, into which the infrared light range is divided, and the subject is sequentially illuminated with light of the respective wavelength ranges. The light reflected on the subject is then sequentially imaged by the image sensor and is synthesized, while the IR1, IR2 and IR3 wavelength ranges are assigned to the respective channels Bch, Gch and Rch corresponding to blue (B), green (G) and red (R). The process generates a video signal of an image of blood vessel arrangement (pseudo-color display).
Next, with reference to a conceptual diagram shown in FIG. 14, the electronic endoscope device disclosed by JP 1-43228 A is described, in which a normal light image and an oxygen saturation level image are switched to one another to be displayed.
The operation for observing a normal light image is same as that of the electronic endoscope device in which a normal light image and an image of blood vessel arrangement are switched to one another to be displayed.
When observing an oxygen saturation level image, light in the visible light range emitted from a lamp is sequentially turned, by a rotary filter, into light in three wavelength ranges G1, G2 and G3, into which the green light range is divided, and the subject is sequentially illuminated with light in the respective wavelength ranges. The light reflected on the subject is then sequentially imaged by the image sensor and is synthesized, while the G1, G2 and G3 wavelength ranges are each assigned to the channels Bch, Gch and Rch corresponding to B, G and R. The process generates a video signal of an oxygen saturation level image (pseudo-color display).